As for a conventional apparatus for manufacturing a casting, a single part production has been carried out by using a two-part mold. That is, while the temperature of joined mold parts is kept within a range near the upper limit of the solid-solution phase temperature of an aluminum alloy, inorganic particles are charged into a cavity in the mold. The pressure in the cavity of the mold is reduced by vacuum-suction from one end of the cavity, while molten metal of the aluminum alloy at the liquid phase temperature is suction-injected from the other end into fine gaps among the particles in the inorganic particle layers in the cavity so that a composite member having predetermined dimensions is manufactured.
However, it is difficult to keep sealing between joint surfaces of the joined mold parts. Particularly when the temperature of the mold is high as mentioned above, a gap may be produced between the joint surfaces of the mold because of the warp of the mold caused by a temperature difference between the mold temperature and the outside air temperature. Accordingly, it becomes further difficult to keep the sealing between the joint surfaces of the mold. Therefore, reduction of pressure in the cavity cannot be attained when the pressure in the cavity is reduced by vacuum-suction after inorganic particles are charged into the cavity of the joined mold, so that molten metal cannot be suction-injected into the joined mold.
To attain the reduction of pressure in the cavity of the mold at the time of vacuum-suction, a heat-resistant packing may be attached to the joint surfaces of the mold. However, there is no suitable packing material which can keep a desired vacuum at such a high temperature. Even if metal packing material which can be proof against high temperature is used, it is inferior in durability. Particularly in a mold of the type in which opening and closing are repeated, the sealing between the joint surfaces of the mold is lost when the elasticity of the metal packing material is lost, and the effect of packing is therefore lost.
It is an object of the present invention to provide a method of manufacturing a casting and an apparatus therefor, in which joint surfaces of mold can be sealed without using any packing material.